1. Field of the Invention
The present invention relates to a method of manufacturing a low pressure injection type RIM mold and a product molded using the mold. More particularly, the present invention relates to a method of manufacturing a low pressure injection type RIM mold and a product molded using the mold, wherein manufacturing time is reduced by simplifying manufacturing processes and the precision of a product is prevented from being lowered, that is, a more precise product can be manufactured by reducing manufacturing time to prevent the deformation of the product due to shrinkage and costs can be reduced by eliminating needs for sheet materials and manufacture of a mock-up.
2. Description of the Prior Art
Generally, as for product molding methods, there are extrusion molding, injection molding and the like. In such molding methods, a mold for producing a desired product is first manufactured and a material is injected into the mold to produce the product.
In case of the injection molding, many apparatuses are required since products are produced by injecting a material into a mold under high pressure. On the contrary, in case of producing products in small quantities, the products are generally produced by manufacturing a simple mold called “RIM mold” and injecting a material into the mold under low pressure.
FIGS. 1 to 5 are schematic views illustrating respective steps of a conventional method of manufacturing a RIM mold. The conventional method of manufacturing the RIM mold comprises the following steps.
First, the step illustrated in FIG. 1 is the step of forming a “skin” material based on skin data on a product. In this step, a base 1 made of plywood is prepared and a mock-up 2 is then prepared on the base 1 by performing pre-forming operations using wood or resin and NC machining.
As shown in FIG. 2, an outer frame 3 is prepared around the mock-up 2 after the mock-up 2 has been prepared as described above. Then, a gel coat 4 is stacked on the mock-up 2 and reinforcing epoxy 5 is stacked on the gel coat 4, thereby preparing a lower mold 6.
Thereafter, as shown in FIG. 3, the lower mold 6 is released and inverted after the epoxy resin of the lower mold has been completely cured. Then, wax or resin 7 is stacked on the inverted lower mold 6 and then subjected to machining for the thickness of a product, bosses and a rim.
Then, an upper mold 8 is prepared by stacking a gel coat 4 on the machined surface and stacking reinforcing epoxy 5 on the gel coat (FIG. 4). As shown in FIG. 5, the upper mold 8 is released and the thickness-defining portion is then removed.
Subsequently, a material is injected into a gate of the mold with low pressure (atmospheric pressure) to produce a product.
However, such a conventional method of manufacturing the mold described above has a problem in that a great deal of manufacturing time is required due to the complicated processes. Further, it has a problem in that since the gel coat, the reinforcing epoxy and the like are stacked on the prepared skin material and the upper mold is then prepared thereon as described above, it is not possible to accurately reproduce the shape of products, resulting in deterioration of the precision of the products.